This invention relates to an audio data reproducing system or device for a digital VTR having a function of signal reproduction at differential speeds, i.e. at tape speeds different from the normal tape speed. The device of the present invention may be employed in, for example, a composite digital VTR according to a D-2 format.
The D-2 standard format for a digital VTR provides for three longitudinal tracks, namely a time code track TR.sub.TC for recording time code signals, a control track TR.sub.CTL for recording control signals providing servo reference and a cue audio track TR.sub.CUA for recording cue audio signals for editing, and a slanted track TR.sub.PRG for recording digital video signals and digital audio signals, as shown in FIG. 1. The single slanted track TR.sub.PRG is constituted by a central video sector VS and audio signal sectors AS.sub.1, AS.sub.2 ahead and back of the central sector VS.
In the D-2 format digital VTR, 1-field digital video signals are recorded, along with digital audio signals, by 3 segments or 6 tracks by two pairs of recording rotary magnetic heads mounted on a rotary drum at an angular interval of 180.degree., while the digital video signals and digital audio signals, recorded in this manner on the recording tape, are reproduced by two pairs of playback rotary magnetic heads mounted on the rotary drum at an angular interval of 180.degree..
In general, in a helical-scan video tape recorder for recording/reproducing video signals on or from slanted tracks on the magnetic tape, it is necessary for a playback rotary magnetic head to trace the slanted track correctly. Consequently, dynamic playback control is performed for differential speed playback in which a playback rotary magnetic head, or a so-called dynamic tracking head (DT head), is moved in a direction of traversing the slanted track on the magnetic head by a head moving unit employing an electro-mechanical transducer, such as a bimorph.
Meanwhile, in analog VTR, the playback sound conforming to the playback image may be produced even during differential speed playback by reproducing audio signals recorded on a longitudinal audio track.
On the other hand, in a digital VTR according to the above-mentioned D-2 standard in which audio signals are also digitized and recorded/reproduced as PCM audio signals, video data and audio data recorded on the slant, ed track are read and reproduced during the low-speed playback mode of reproducing recorded data at a speed lower than a normal playback speed. Consequently, during the low-speed playback mode, the same slanted track is to be repeatedly traced by the DT head. The result is that, in the case of the digital VTR, the voice cannot be reproduced so smoothly as in the case of sound recorded on the longitudinal audio track of the analog VTR.
That is, in digital VTR, the picture and the sound are repeatedly obtained for each field or frame. In conventional digital VTR, the audio data obtained repeatedly in this manner is decoded and directly outputted, so that a continuous block of sound, that is the lump-like sound for each field or frame, is heard repeatedly, whereas a similar sound is also reproduced during still playback.